So i encountered this same exact error with a fresh build and figured it out, at least on my end.

There were three things I did not do or did 'incorrectly' when setting up this VCSA on our lab at the office below with changed effect:

1. Did not setup a proper fqdn: i had set it up as an IP address and not a resolving fqdn, going forward I set it to vc.thegrid.net (testing domain)

2. Configured 2 NTP servers when 1 was offline: discovered this when trying to see if instead we could do an upgrade path and doing a fresh install for VCSA 6.0U2 threw a warning that it WILL fail since one of the NTP servers listed is unreachable.

3. Set up 2 DNS servers when 1 was offline: same as #2, but there was no warning when setting up 6.0U2 however i omitted the third server just because.

So my 2 cents would be to set a properly resolvable FQDN, and point to 1 NTP and DNS server that is online, make edits to 2+ servers later on.